Brazil came from behind to beat a stubborn Croatia 3-1 with the help of Neymar’s double in a nervous-but-successful start to their home World Cup title mission.

The young icon was on target with a low shot in the 29th minute and on a disputable penalty in the 71st before Oscar wrapped up matters late after an own goal from Marcelo had given Croatia a shock lead early on.

Neymar’s goals, which set off fireworks across Sao Paulo and elsewhere, were the perfect start for himself and for Brazil in their bid for a sixth title.

Luiz Felipe Scolari’s men will need to improve after they had a hard time breaking down a disciplined Croatian defence. But they can draw optimism from Neymar seemingly not cracking under the immense pressure, and the recently-criticised Oscar also showing a strong performance on the left wing and scoring as well.

The host nation's Group A victory was greeted by an explosion of fireworks across Sao Paulo, a sharp contrast to several hours earlier when riot police fired tear gas and stun grenades to disperse angry protests.

But a largely free-flowing tournament-opener was shrouded in controversy, with Brazil's second coming courtesy of a dubious penalty when Croatia defender Dejan Lovren was harshly adjudged to have shoved Fred.

The hosts, chasing a record sixth World Cup, had also enjoyed a degree of good fortune in the first half when Neymar received only a yellow card for elbowing Croatia's playmaker Luka Modric.

Moments later Neymar scored Brazil's equaliser to settle home nerves after Marcelo's 11th-minute own goal.

Nishimura's performance comes as further embarrassment for FIFA after months of public protests and strikes in Brazil, and with soccer's ruling body battling renewed allegations of corruption over its award of the 2022 World Cup to Qatar.

The influential Jutarnji List daily slammed "inexcusable mistake by the referee at the World Cup opening match" by which he "pierced Croatia's heart with a sword."

Anticipating further backlash against Nishimura, Japanese fan @tonbuhin tweeted: "Oh dear, if Brazil win the World Cup the whole world will say Nishimura was the MVP (most valuable player)."